Been using Eclipse for a long time as a java developer.
My PC was upgraded to windows 7. To be more precise my main drive was completely wipe out with a new image.
Started re-installing stuff.
Dowloaded lastest eclipse IDE for JAVA EE Developers eclipse-jee-indigo-SR2-win32-x86_64.zip (v. 3.7.2, build)
Unzipped in C:\Program Files\Eclipse3-7-2-64
Installed 64 bits jdk in C:\Program Files\Java\jdk1.6.0_31

(tried both with "" or without around the path to javaw.exe e.i. "C:\Program Files\Java\jdk1.6.0_31\bin\javaw.exe" does not seem to make any difference)
Anyway as far as I know this is the only java on my machine since I just installed it before eclipse.
No matter what I do, eclipse does not start, I always get....
(in my Users\<my name>\.eclipse\org.eclipse.platform_3.7.0_1211405066\configuration\

!ENTRY org.eclipse.equinox.p2.reconciler.dropins 4 0 2012-04-10 09:27:41.333
!MESSAGE FrameworkEvent ERROR
!STACK 0
org.osgi.framework.BundleException: The bundle "org.eclipse.equinox.p2.reconciler.dropins_1.1.100.v20110815-1419 [289]" could not be resolved. Reason: Missing Constraint: Require-Bundle: org.eclipse.equinox.p2.touchpoint.eclipse; bundle-version="1.0.0"
at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1327)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1311)
at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:323)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:389)
at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1131)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:559)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:544)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:457)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:438)
at org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:1)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:340)

Don't put eclipse in Program Files on Windows 7. Windows places restrictions on this folder that makes running programs difficult.

Make sure that you keep the folder structure intact when you unzip the eclipse zip file. There needs to be a specific directory hierarchy under the root directory for Eclipse to be able to find its components.

I never touched anything in the file srtucture excepting editing eclipse.ini

Here is what worked, I already did wipe out everything and re-did it, just to be sure everything was the same and got the same result. With a colleague we again wiped out everything (including) the .eclipse in my Users/myname folder. We did exactly what you suggested, we did not put it Program Files, and it worked right away! But here is the kicker, after it worked once, I actually put it again at the exact same location and now it works. So why did it not work properly in the first place is still a mystery?

If ever somebody else as a similar problem I would be curious to understand what cause the initial issue.

I would recommend moving Eclipse out of Program Files under Windows 7. It may work now, but there may come a time when you run into a permission problem that again prevents things from working. This can happen when you try to update the software or install new software. Program Files is treated as a special location by Windows 7 and the OS places restrictions on what programs can change in this directory.